1. Field of the Invention
The invention relates to reactions wherein vapor and/or gas bubbles are produced and rising in a fluid. More particularly, the invention relates to reactions wherein autorefrigeration or sparging is employed.
2. Background of the Art
A number of known reactions may be characterized as including a vapor phase. Some of these reactions involve introduction of a gas through a means such as a sparger. These gases may include, for example, air, oxygen or nitrogen. Other reactions are those categorized as autorefrigeration reactions. In these reactions a solvent-diluent medium is vaporized from a liquid phase in order to remove the exothermic head of reaction and maintain a substantially constant temperature in the medium remaining in solution. In these cases the vaporized solvent-diluent is usually recovered via, for example, a condenser, and the recovered solvent-diluent is returned to the reactor. This solvent-diluent may be a single material such as toluene; a constant boiling azeotrope such as benzenecyclohexane, or a reactant in the system. Temperature control in these cases thus requires a vapor space in the reaction vessel into which the vaporized solvent-diluent medium expands. Some of the solution medium is frequently entrained in the vapor phase and must then be removed separately because it may foul the solvent-diluent vapor removal means.
When either of the above-described types of reactions is carried out in conventional autorefrigeration or sparging vessels, the rising vapor and/or gas bubbles induce significant axial, or back, mixing. Such mixing tends to broaden the residence time distribution, and may also undesirably affect the product being produced. The residence time within these types of vessels is therefore generally comparable to that of continuous stirred tank reactors (CSTRs).
In view of the above, it would be desirable to have an autorefrigerated reactor or sparging vessel wherein back mixing is reduced and, therefore, residence time distribution may be narrowed.